1. Field of the Invention
The invention relates to the formation of color filters, more particularly to an apparatus for making a color filter.
2. Description of the Related Art
Referring to FIGS. 1 to 3, a conventional optical projection device, as disclosed in U.S. Pat. No. 5,868,482, is shown to include a color wheel assembly 1, a light source 2, a picture generating device 3, an optical projection system 4, and a screen 5. The color wheel assembly 1 has a motor 101, a carrier 102 mounted on a shaft of the motor 101, an adhesive layer 103 coated on the carrier 102, three sector-shaped filter segments 104 that are adhered to the adhesive layer 103 and that cooperate to form a ring shape, and a retaining ring 105 for retaining the filter segments 104 on the carrier 102. Accordingly, when the motor 101 rotates the carrier 102, light beams projected from the light source 2 can pass through the filter segments 104 in sequence, and to the picture generating device 3, after which, the picture produced by the picture generating device 3 is projected on the screen 5 through the optical projection system 4.
In general, the rotational speed provided by the motor 101 for the filter segments 104 is related to the picture refresh rate, and is in a range of several thousand revolutions per minute. As such, during rotation, the filter segments 104 can encounter considerable centrifugal forces of up to a thousand times greater than the weight thereof.
Referring again to FIG. 3, the filter segments 104 are cut from three individual plates 6, which are respectively coated with different colors, such as red (R), green (G), and blue (B), and which are then adhered to the carrier 102 (see FIG. 2) so as to form a ring shape.
Since the filter segments 104 are not formed integrally, during high-speed rotation, problems of imbalance due to non-uniform tolerable strengths can occur. Furthermore, since the filter segments 104 have to be cut from three separate plates 6, which are colored beforehand and which are thereafter adhered to the carrier 102, not only is the production both troublesome and inconvenient, control of the stability and precision of the filter segments 104 is also difficult.